This invention relates generally to electronic control circuits and particularly to an electronic temperature control circuit.
It is generally desired to utilize different temperature sensors for sensing the temperature which may then be used for controlling a resistive heating element. Thus, it may be desired to utilize, besides the thermocouple to which the prior application is directed, other temperature sensors such as a resistive sensor or a thermistor. Furthermore, it is desirable to utilize either positive or negative temperature coefficient devices. A positive temperature coefficient simply means that the sensor's resistance increases with a rising temperature. A sensor having a negative temperature coefficient exhibits a resistance which decreases with rising temperature.
It is furthermore desirable to provide circuits which are capable of operating with different voltages which may be either alternating current or direct current voltages.
Besides controlling the temperature of a heater element, it is also possible to provide a digital display to compensate for variations of the temperature of the cold junction of a thermocouple and to compensate automatically for the nonlinearity of the sensor signal.